This invention relates to a humidifier with a floating evaporative wick with replaceable wick elements or cartridges having a constant area evaporative surface on its wicking elements.
Generally, room humidifiers are utilized to add moisture to dry air within a room being heated so as to maintain the relative humidity in the room within a desired comfort range. As is widely recognized, during the winter heating season, humidity levels within heated rooms tend to be quite low because the moisture content of the outside air is low such that when the atmospheric air is heated, low relative humidities within a room result. Low relative humidity causes excessive static electricity, discomfort to the occupants of the room, drying out furniture and plants, and numerous other problems.
Heretofore, room humidifiers were generally of a variety of types. In a first type, water was sprayed onto an evaporative filter by means of a pump and air was then drawn through the pad for evaporating the water sprayed thereon and for discharging the humidified air into the room. Reference may be made to U.S. Pat. No. 3,914,349, which discloses such a humidifier. As is typical, the pumps for such humidifiers consisted of a vertically disposed centrifugal impeller which picked up water from a water reservoir and which sprayed the water radially outwardly onto the inner surface of the pad surrounding the pump. Air would then be forced by the fan through the pad so as to cause the evaporation of the water. However, these humidifiers typically required a water level control so as to maintain a relatively constant supply of water being fed to the pump. Alternatively, other humidifiers were known which had variable evaporative areas on their pads, thus resulting in variable rates of water evaporation and humidification depending on the exposed evaporative area. Other examples of such centrifugal pumps/evaporative filter humidifiers may be seen by referring to U.S. Pat. Nos. 3,220,707, 3,294,376, 3,348,821, 3,348,822, 3,552,097, 3,953,551, 4,301,094, and 4,350,646.
Other humidifiers were known in which a wicking or evaporative element was at least in part submerged in a water bath and in which air was blown over the wetted wicking element so as to evaporate water therefrom. However, such immersed filter or wicking element humidifiers required a separate reservoir or water supply which fed water to an evaporative sump by means of a float control valve thereby to maintain a substantially constant water level wetting the evaporative pad. Reference may be made to U.S. Pat. No. 2,031,055 for a more complete disclosure of such a humidifier.
Still further, other humidifiers were known which utilized a motor driven belt evaporative pad or wicking element which was entrained around rollers and which extended into a water reservoir for wetting the evaporative belt or pad. The wetted belt then rose out of the water supply and room air was forceably drawn over the belt thereby to evaporate water therefrom and to humidify the air.
A number of long-standing problems have been associated with all of the above-described types of room humidifiers. With centrifugal pump/filter humidifiers, the combination of the required pump and fan added substantially to the mechanical complexity and cost of the unit. The centrifugal pump oftentimes had a tendency to clog with mineral deposits. In addition, in order for the filter/evaporative pad to have a constant surface area, it was often necessary to have a separate water supply tank feeding water to the pump by means of a control valve which maintained a constant water level at the pump inlet. Again, this added to the complexity and cost of the unit and, due to mineral deposits, required that these parts be periodically cleaned to maintain them in a workable condition over extended periods of time. Further, the filter/evaporative pads of these centrifugal pump-type humidifiers experienced mineral build-up thereon which in turn required replacement or cleaning. However, it was a relatively difficult and expensive matter to remove and replace these clogged filter/evaporative pads.
In humidifiers both of the fixed evaporative pad construction and of the movable belt pad construction, several additional problems have long been noted. First, in regard to the fixed pad evaporative unit, such as shown in U.S. Pat. No. 2,031,055, the evaporative efficiency of such humidifiers is oftentimes dependent on the capillarity capabilities of the evaporative pad and the area of the pad in contact with the water supply. It will be appreciated that as the water is drawn up from the water supply and evaporated from the pad, mineral deposits, both soluble and insoluble deposits, remain on the pad, thus significantly decreasing its surface area and its evaporative efficiency. Additionally, these mineral deposits tend to diminish the capillarity characteristics of the evaporative pad. Thus, the pads must be periodically cleaned or replaced which is a rather cumbersome job.
In regard to the rotary belt humidifiers in which an endless belt is entrained around rollers to pass through a water supply and then to be exposed to moving air for evaporating water picked up thereon, it will be appreciated that mineral deposits will also remain on the belt. However, because the belt continuously passes through the water, soluble salts and other soluble deposits will be redissolved into the water supply. Additionally, movement of the belt being entrained around a roller disposed below the level of the water supply tends to dislodge insoluble mineral deposits. Because the soluble deposits from the belt are again dissolved in the water supply, this has the effect of substantially increasing the concentration of these soluble minerals in the water supply. Thus, over time, as the concentration of these soluble mineral deposits accumulates in the water supply and as the insoluble mineral deposits build up on the bottom of the water supply tank or reservoir, the increased concentrations of the soluble dissolved minerals in the supply water will be carried onto the movable evaporative pad and will be deposited thereon in relatively high concentrations so as to markedly reduce the evaporative efficiency of the pad. Thus, in such rotary belt humidifiers, it is required that the belt pads be periodically replaced which is a time-consuming job requiring substantial disassembly of the humidifier.
Also, because of the above-noted increased concentrations of minerals in the supply water, certain of these precipatate out of solution and form a thick coating on all parts of the humidifier below the water level. Removal of these mineral deposits is difficult. Certain "anti-scale" chemical additives are oftentimes used to combat such buildup, but these "anti-scale" chemical additives merely turn the hardened crust into or gel still leaving a difficult cleanup job.
U.S. Pat. No. 3,864,437 and German Patent No. 3,312,367 disclose humidifiers which have floating evaporative pads, they either utilize complicated accordion-like sidewalls or bellows, to direct air flow between the fan and the evaporative fan, or blow unducted air downwardly on a pad.
There has been a long-standing need for a portable room humidifier which maintains a constant evaporative area on the wicking or filter pad without the requirement of complicated float valves and the like to maintain a constant water level. There has also been a long-standing need for a humidifier in which the evaporative wicking pad may be readily removed for cleaning or replacing thereby to maintain the evaporative efficiency of the humidifier within a desired range. There has also been a long-standing need for an evaporator which eliminates the necessity of a centrifugal pump, and yet which does not necessitate the use of complicated float control valves, and which does not increase the concentration levels of soluble minerals dissolved in the water supply.